You'll still have to pay the extra I'm afraid, glasses or no glasses.
IMHO It's a horribly cynical ploy from cinemas to weedle more money out of us, while the "new" 3d is much better visually than any I've seen before, it still adRAB nothing to the actually enjoyment of a film, in fact it just makes it a much LESS immersive experience if you ask me, as (personally) I just spend the entire film re-adjusting the glasses so they don't fall off my unnaturally large head, or making sure they're at exactly the right angle so the frames don't obscure all four corners of the screen.